/*
 * Copyright (C) 2006 Joe Walnes.
 * Copyright (C) 2006, 2007, 2009, 2013 XStream Committers.
 * All rights reserved.
 *
 * The software in this package is published under the terms of the BSD
 * style license a copy of which has been included with this distribution in
 * the LICENSE.txt file.
 * 
 * Created on 04. June 2006 by Joe Walnes
 */
package com.feilong.lib.xstream.io.binary;

import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;

import com.feilong.lib.xstream.io.StreamException;

/**
 * Represents the Tokens stored in the binary stream used by
 * {@link BinaryStreamReader} and {@link BinaryStreamWriter}.
 * <p>
 * A token consists of a type and (depending on this type)
 * it may additionally have an ID (positive long number)
 * and/or a value (String).
 * </p>
 * <p>
 * The first byte of the token represents how many subsequent
 * bytes are used by the ID.
 * </p>
 *
 * @author Joe Walnes
 * @see BinaryStreamReader
 * @see BinaryStreamWriter
 * @since 1.2
 */
public abstract class Token{

    private static final byte   TYPE_MASK            = 0x7;

    public static final byte    TYPE_VERSION         = 0x1;

    public static final byte    TYPE_MAP_ID_TO_VALUE = 0x2;

    public static final byte    TYPE_START_NODE      = 0x3;

    public static final byte    TYPE_END_NODE        = 0x4;

    public static final byte    TYPE_ATTRIBUTE       = 0x5;

    public static final byte    TYPE_VALUE           = 0x6;

    private static final byte   ID_MASK              = 0x38;

    private static final byte   ID_ONE_BYTE          = 0x08;

    private static final byte   ID_TWO_BYTES         = 0x10;

    private static final byte   ID_FOUR_BYTES        = 0x18;

    private static final byte   ID_EIGHT_BYTES       = 0x20;

    private static final String ID_SPLITTED          = "\u0000\u2021\u0000";

    private static final int    MAX_UTF8_LENGTH      = 0xffff;

    private final byte          type;

    protected long              id                   = -1;

    protected String            value;

    public Token(byte type){
        this.type = type;
    }

    public byte getType(){
        return type;
    }

    public long getId(){
        return id;
    }

    public String getValue(){
        return value;
    }

    @Override
    public String toString(){
        return getClass().getName() + " [id=" + id + ", value='" + value + "']";
    }

    @Override
    public boolean equals(Object o){
        if (this == o){
            return true;
        }
        if (o == null || getClass() != o.getClass()){
            return false;
        }

        final Token token = (Token) o;

        if (id != token.id){
            return false;
        }
        if (type != token.type){
            return false;
        }
        return !(value != null ? !value.equals(token.value) : token.value != null);
    }

    @Override
    public int hashCode(){
        int result;
        result = type;
        result = 29 * result + (int) (id ^ (id >>> 32));
        result = 29 * result + (value != null ? value.hashCode() : 0);
        return result;
    }

    public abstract void writeTo(DataOutput out,byte idType) throws IOException;

    public abstract void readFrom(DataInput in,byte idType) throws IOException;

    protected void writeId(DataOutput out,long id,byte idType) throws IOException{
        if (id < 0){
            throw new IOException("id must not be negative " + id);
        }
        switch (idType) {
            case ID_ONE_BYTE:
                out.writeByte((byte) id + Byte.MIN_VALUE);
                break;
            case ID_TWO_BYTES:
                out.writeShort((short) id + Short.MIN_VALUE);
                break;
            case ID_FOUR_BYTES:
                out.writeInt((int) id + Integer.MIN_VALUE);
                break;
            case ID_EIGHT_BYTES:
                out.writeLong(id + Long.MIN_VALUE);
                break;
            default:
                throw new Error("Unknown idType " + idType);
        }
    }

    protected void writeString(DataOutput out,String string) throws IOException{
        final byte[] bytes = (string.length() > MAX_UTF8_LENGTH / 4) ? string.getBytes("utf-8") : new byte[0];
        int length = bytes.length;
        if (length <= MAX_UTF8_LENGTH){
            out.writeUTF(string);
        }else{
            out.writeUTF(ID_SPLITTED);
            out.writeInt(bytes.length);
            out.write(bytes);
        }
    }

    protected long readId(DataInput in,byte idType) throws IOException{
        switch (idType) {
            case ID_ONE_BYTE:
                return in.readByte() - Byte.MIN_VALUE;
            case ID_TWO_BYTES:
                return in.readShort() - Short.MIN_VALUE;
            case ID_FOUR_BYTES:
                return in.readInt() - Integer.MIN_VALUE;
            case ID_EIGHT_BYTES:
                return in.readLong() - Long.MIN_VALUE;
            default:
                throw new Error("Unknown idType " + idType);
        }
    }

    protected String readString(DataInput in) throws IOException{
        final String string = in.readUTF();
        if (!ID_SPLITTED.equals(string)){
            return string;
        }
        final int size = in.readInt();
        final byte[] bytes = new byte[size];
        in.readFully(bytes);
        return new String(bytes, "utf-8");
    }

    public static class Formatter{

        public void write(DataOutput out,Token token) throws IOException{
            long id = token.getId();
            byte idType;
            if (id <= Byte.MAX_VALUE - Byte.MIN_VALUE){
                idType = ID_ONE_BYTE;
            }else if (id <= Short.MAX_VALUE - Short.MIN_VALUE){
                idType = ID_TWO_BYTES;
            }else if (id <= (long) Integer.MAX_VALUE - (long) Integer.MIN_VALUE){ // cast to long to prevent overflow
                idType = ID_FOUR_BYTES;
            }else{
                idType = ID_EIGHT_BYTES;
            }
            out.write(token.getType() + idType);
            token.writeTo(out, idType);
        }

        public Token read(DataInput in) throws IOException{
            byte nextByte = in.readByte();
            byte type = (byte) (nextByte & TYPE_MASK);
            byte idType = (byte) (nextByte & ID_MASK);
            Token token = contructToken(type);
            token.readFrom(in, idType);
            return token;
        }

        private Token contructToken(byte type){
            switch (type) {
                case Token.TYPE_START_NODE:
                    return new StartNode();
                case Token.TYPE_MAP_ID_TO_VALUE:
                    return new MapIdToValue();
                case Token.TYPE_ATTRIBUTE:
                    return new Attribute();
                case Token.TYPE_END_NODE:
                    return new EndNode();
                case Token.TYPE_VALUE:
                    return new Value();
                default:
                    throw new StreamException("Unknown token type");
            }
        }
    }

    public static class MapIdToValue extends Token{

        public MapIdToValue(long id, String value){
            super(TYPE_MAP_ID_TO_VALUE);
            this.id = id;
            this.value = value;
        }

        public MapIdToValue(){
            super(TYPE_MAP_ID_TO_VALUE);
        }

        @Override
        public void writeTo(DataOutput out,byte idType) throws IOException{
            writeId(out, id, idType);
            writeString(out, value);
        }

        @Override
        public void readFrom(DataInput in,byte idType) throws IOException{
            id = readId(in, idType);
            value = readString(in);
        }

    }

    public static class StartNode extends Token{

        public StartNode(long id){
            super(TYPE_START_NODE);
            this.id = id;
        }

        public StartNode(){
            super(TYPE_START_NODE);
        }

        @Override
        public void writeTo(DataOutput out,byte idType) throws IOException{
            writeId(out, id, idType);
        }

        @Override
        public void readFrom(DataInput in,byte idType) throws IOException{
            id = readId(in, idType);
        }

    }

    public static class EndNode extends Token{

        public EndNode(){
            super(TYPE_END_NODE);
        }

        @Override
        public void writeTo(DataOutput out,byte idType){
        }

        @Override
        public void readFrom(DataInput in,byte idType){
        }

    }

    public static class Attribute extends Token{

        public Attribute(long id, String value){
            super(TYPE_ATTRIBUTE);
            this.id = id;
            this.value = value;
        }

        public Attribute(){
            super(TYPE_ATTRIBUTE);
        }

        @Override
        public void writeTo(DataOutput out,byte idType) throws IOException{
            writeId(out, id, idType);
            writeString(out, value);
        }

        @Override
        public void readFrom(DataInput in,byte idType) throws IOException{
            this.id = readId(in, idType);
            this.value = readString(in);
        }

    }

    public static class Value extends Token{

        public Value(String value){
            super(TYPE_VALUE);
            this.value = value;
        }

        public Value(){
            super(TYPE_VALUE);
        }

        @Override
        public void writeTo(DataOutput out,byte idType) throws IOException{
            writeString(out, value);
        }

        @Override
        public void readFrom(DataInput in,byte idType) throws IOException{
            value = readString(in);
        }

    }

}
